Stems to 1 m, with short, leafy axillary branches, pubescent with short, usually downcurved hairs or longer spreading hairs or both; lvs narrowly lanceolate, entire or shallowly serrate, the largest ones median, 4.5-9.5 נ1-2.5 cm, on petioles 3-6 mm; upper lf- surfaces with scattered hairs, the lower with longer spreading hairs especially on the main veins; glomerules relatively loose and open, each subtended by a pair of lf-like, evenly pubescent bracts; cal 3.5-5 mm, short- hairy, weakly bilabiate, its teeth narrowly deltoid, somewhat acuminate, ciliate with several jointed bristles at the tip, the upper 3 ca 2/3 as long as the lower pair, these 0.5-2 mm; nutlets glabrous, or hairy at the tip; 2n=76. Locally near the coast from Mass. to N.C. Sometimes thought to reflect hybridization of nos. 4 [Pycnanthemum incanum (L.) Michx.] and 11 [Pycnanthemum verticillatum (Michx.) Pers.].
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
